The present invention relates to apparatus for operating a pneumatic actuator and more particularly to such apparatus which provides direct response to digital electronic controllers.
In general, it has heretofore been relatively difficult to operate pneumatic actuators directly from electric signals as generated by electronic controllers, analog or digital in nature. Accordingly, for applications where such controllers are used it has typically been necessary to utilize complex transducers to convert analog or digital signals to pneumatic signals, a situation that entails higher cost and degradation of the system's precision and dynamic response.
By and large, pneumatic actuators as known heretofore have not been well adapted for use in systems employing electronic controllers. In particular, such previous art actuators have not been suitable for operating directly from digital logic or pulse controllers. Such controllers are experiencing generally increased popularity due to their flexibility and programmability.
Furthermore, most pneumatic actuators and control systems known previously have entailed a constant air bleed whether or not the actuator was producing any movement, a condition detrimental to the actuators's energy efficiency.
Among the several objects of the present invention may be noted the provision of novel apparatus for operating a pneumatic actuator; the provision of such apparatus which facilitates precise control of a pneumatic actuator; the provision of such apparatus which facilitates the use of digital controllers in operating a pneumatic actuator within an overall servo system; the provision of such apparatus which can be operated efficiently and at low cost; the provision of such apparatus which is highly reliable and which is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.